Major
Dronedarone × Escitalopram
Class III antiarrhythmic×Selective serotonin reuptake inhibitors (SSRIs)
Mechanism
Both drugs prolong QT. Escitalopram does so dose-dependently (FDA Lexapro caps at 20 mg/day), dronedarone does too. Effects add up.
Symptoms
QT prolongation on ECG. Clinically: dizziness, syncope, palpitations. Severe cases progress to polymorphic ventricular tachycardia (torsades de pointes). Risk is higher with hypokalaemia, hypomagnesaemia, bradycardia, and ischaemic heart disease.
Management
Avoid the combination. If escitalopram is needed, cap at 10 mg/day; ECG before start and at 2 weeks; maintain potassium and magnesium. Alternative antidepressants: mirtazapine or agomelatine.